Video encoding apparatus

ABSTRACT

In a video encoding apparatus of the invention, a video camera is provided with a moving direction detecting means for detecting movement of the camera in preset moving direction and outputting a detecting signal, a movement information generator is installed for operating the displacement amount of the video camera based on the detecting signal outputted from the moving direction detecting means and calculating the specific position on the memory corresponding to the operated displacement amount of the video camera and outputting the position to a reference signal generator, and plural blocks stored to the specific position on the frame memory are read based on output from the movement information generator.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a video encoding apparatus which isapplied, for example, to a video communication system.

2. Description of the Prior Art

FIG. 1 shows an example of such apparatus in the prior art, particularlya video encoding apparatus of the movement compensation type. In FIG. 1,numeral 1 designates an A/D converter which receives video signalsoutputted from a video camera 8 and converts the signals inanalog/digital conversion and then outputs them. A block constitutingmember 2 receives the digital signal series outputted from the A/Dconverter 1 and makes every K picture elements close on the pictureimage (K: integer not less than 2) in a block and outputs the signals inthe block. A frame memory 3 stores data transmitted one frame before theexisting input signal frame and supplied through an adder 10. Areference signal generator 4 reads from the frame memory 3 the inputblock including the existing input signal series constituted into ablock in the block constituting member 2 and also plural blocksincluding the block at the same position on the picture image and formedby the signal series which is one frame before the existing frame. Adistortion operation member 5 operates distortion between the signalseries of the input block outputted from the block constituting member 2and the signal series of the plural blocks stored in the frame memory 3,and outputs the position information of the block giving the minimumdistortion and the existing signal series. A subtractor 6 estimatesdifference signal series (vector) between the signal series of the inputblock outputted from the block constituting member 2 and the signalseries of the block giving the minimum distortion and outputted from thedistortion operation member 5, and then outputs the difference signal. Aquantization encoding member 7 receives the difference signal series(vector) outputted from the subtractor 6 and performs quantizationencoding of the difference signal. A quantization decoding member 9reproduces the difference signal series from the quantization encodingsignal outputted by the quantization encoding member 7. An adder 10 addsthe quantization decoding output from the quantization decoding member 9to the signal series of the block giving the minimum distortion andoutputted from the distortion operation member 5, and reproduces thevideo signal and writes it to the frame memory 3.

The principle of the vector quantization will now be briefly describedreferring to FIG. 2.

The information source input signal series of K in number are broughttogether into input vector x={x₁, x₂, . . . , x_(K) }. Then, theK-dimensional Euclidean signal space R^(K) (xεR^(K)) has therepresentative points of N in number (i.e., output vector) y_(i)={Y_(i1), Y_(i2), . . . , Y_(iK) }, and set of the representative pointsis made Y={y₁, y₂, . . . , y_(N) }. If each partition of R^(K) havingoutput vector y_(i) as the representative point (e.g., center ofgravity) is made R₁, R₂, . . . , R_(N), vector quantization Q is definedby the following formula:

    Q:R.sup.K →Y                                        (1)

wherein ##EQU1## The vector quantization Q is expressed as a cascadeconnection of encoding C and decoding D. The encoding C is a mapping ofthe output vector set Y={y₁, y₂, . . . , y_(N) } of R^(K) to index setI={1, 2, . . . , N}, and the decoding D is a mapping from I to Y. Thatis,

    C:R.sup.K →I, D:I→Y                          (4)

    Q=D·C                                             (5)

Since the encoding output I is transmitted or recorded in the vectorquantization, the encoding efficiency is quite good.

The vector quantization is the mapping of the input vector to the outputvector y_(i) in the minimum distance (minimum distortion). Morespecifically, if distance (distortion) between input/output vector ismade d(x, y_(i)), it follows that

    if d(x, y.sub.i)<d(x, y.sub.j) for all j                   (6)

    xεR.sub.i hence x→y.sub.i                   ( 7)

Set Y of the output vector y_(i) as shown in FIGS. 3(A) and 3(B) can bedetermined by clustering using the information source input signalseries being the training model (repetition of selection of therepresentative points and the partition of signal space until the totaldistortion becomes minimum).

Operation of the apparatus in above-mentioned constitution of FIG. 1will be described. Video signals outputted from the video camera 8 tothe A/D converter 1 are converted into digital signal series by the A/Dconverter 1 and then outputted to the block constituting member 2. Inthe block constituting member 2, every K picture elements close on thepicture image are made a block usually in rectangular form (or squareform) on the picture image, and transformed in the arrangement and thenoutputted to the distortion operation member 5 and the subtractor 6. Onthe other hand, the signal series of the plural blocks, which are storedin the memory 3 and read by the reference signal generator 4, aretransmitted to the distortion operation member 5 in synchronization withthe existing input signal series outputted from the block constitutingmember 2 by the reference signal generator 4. An example of the positionrelation between the block of the existing input signal series outputtedfrom the block constituting member 2 and the plural blocks read by thereference signal generator 4 is shown in FIG. 3(A) illustrating theexisting frame and FIG. 3(B) illustrating the frame being one before theexisting frame. The distortion calculation between the signal series ofthe existing input block and the signal series of the plural blocks isperformed in the distortion operation member 5 using, for example,Euclidean distortion or absolute value distortion. According to thecalculation results, the block to provide the minimum distortion to theexisting input block is selected among the plural blocks. Assuming thatthe blocks as the calculation object are M in number (M: integer notless than 2) and the block to provide the minimum distortion is the l-thone among the M blocks (l=1, 2, . . . , M), the distortion operationmember 5 outputs the value of l and the signal series of the block tothe subtractor 6. The subtractor 6 estimates the difference signalseries (vector) between the signal series of the input block and thesignal series to give the minimum distortion and outputs the differencesignal series to the quantization encoding member 7. The differencesignal series (vector) is subjected to the quantization encoding in thequantization encoding member 7 and then outputted to the quantizationdecoding member 9. Both the difference signal series reproduced by thequantization decoding member 9 and the signal series of the blockoutputted from the distortion operation member 5 and giving the minimumdistortion are outputted to the adder 10 and added by the adder 10 andreproduced in the video signal. The video signal is written in the framememory 3 by the adder 10. The signal processing in the process from thequantization encoding member 7 up to the adder 10 in effect relates tothe subsequent processing by vector of the difference signal seriesestimated in the subtractor 6. The smaller the amount of the differencesignal, i.e., the vector quantity, the higher the efficiency of themovement compensation.

In the manner as described above, the inputted video signal is formed asa block which is used to select the block most resembling those in theformer frame. The newest block is compared to the selected block, thedifference or error component being quantized to form a coded outputsignal, together with information representing which block is the mostresembling one.

The video encoding apparatus in the prior art, particularly the videoencoding apparatus of the movement compensation type is constituted asabove described. For example, even in the movement such as theoscillating motion of the video camera 8 where the moving direction ofthe screen is clear, the efficiency of the movement compensation cannotbe increased in the prior art, because the position relation between theblock as object of the distortion operation stored in the frame memory 3and the input block outputted from the block constituting member 2 isfixed.

SUMMARY OF THE INVENTION

A first object of the invention is to provide a video encoding apparatuswherein if the moving direction of a picture screen is clear theinformation regarding the moving direction is reflected upon themovement compensation; thereby efficiency of the movement compensationcan be improved.

A second object of the invention is to provide a video encodingapparatus wherein, even if signals from a plurality of cameras notsynchronously coupled are suitably changed and inputted, theirregularity of the picture image can be suppressed and made minimum.

A third object of the invention is to provide a video encoding apparatuswherein the irregularity of the picture image can be suppressed and mademinimum and moreover the original picture image can be restored rapidly.

A fourth object of the invention is to provide a video encodingapparatus wherein occurrence of excessive information can be suppressedwhen a block with high approximation exists as a result of thedistortion operation, and storage of the quantization error can besuppressed to the block with high approximation.

A fifth object of the invention is to provide a video encoding apparatuswherein when video signals with high occurrence frequency of significantblocks even using a plurality of reference blocks are inputted theinformation amount is not increased.

A sixth object of the invention is to provide a vector quantizationencoder wherein the encoding efficiency can be significantly improved.

A seventh object of the invention is to provide a vector quantizationencoder wherein memory contents to constitute the output vector codetable of respective stages can be made common.

A eighth object of the invention is to provide a vector quantizationencoder between frames wherein noise of block form in the video signalscan be decreased and band compression of the video signals at highquality is possible.

A ninth object of the invention is to provide a motion picture imagetransmission apparatus wherein coma elimination can be performedadaptably depending on condition of the transmission path withoutimpairing the transmission efficiency, and the picture image of comaelimination can be reproduced as a smooth image.

The first object can be achieved in that a video camera is provided witha moving direction detecting means for detecting the movement of thevideo camera in the present moving direction and outputting thedetecting signal, a moving information generating member is installedfor operating the displacement amount of the video camera on the basisof the detecting signal outputted from the moving direction detectingmeans and estimating the specific position on the frame memorycorresponding to the operated displacement amount of the video cameraand outputting the specific position to the reference signal generatingmember, and a plurality of blocks stored in the specific position on theframe memory are read on the basis of output from the moving informationgenerating member.

The second object can be achieved in that a fluctuation detecting meansis installed for detecting the time fluctuation of synchronous signalsincluded in the inputted video signals, and action of a quantizationencoder is stopped during the fluctuation detecting on the basis ofoutput of the fluctuation detecting means.

The third object is achieved in that a fluctuation detecting means isinstalled for detecting the time fluctuation of synchronous signalsincluded in the inputted video signals, a signal changing means isinstalled for changing the input to a quantization encoder from adifference signal between frames into an input video signal on the basisof output of the fluctuation detecting means, action of the quantizationencoder is stopped during the fluctuation detecting on the basis ofoutput of the fluctuation detecting means, and the signal changing meansperforms the changing from the input video signal into the differencesignal between frames by providing delay of one frame of the input videosignal after the fluctuation cannot be detected.

The fourth object is achieved in that a distortion operation means isinstalled for operating distortion between signal series of an inputblock in the last video signal inputted through means for making a blockand signal series of plural blocks read from a video signal storingmeans by a reading means corresponding to the input block and outputtingthe minimum distortion and the position information and the signalseries of the block to provide the minimum distortion, a comparisonmeans is installed for comparing the minimum distortion value with theprescribed threshold value, a quantization encoding means is installedfor performing quantization encoding of difference signal series betweenthe signal series of the input block and the signal series of the blockto provide the minimum distortion, a writing means is installed foradding the difference signal series reproduced from the quantizationencoding output through a quantization decoding means to the signalseries of the block to provide the minimum distortion on the basis ofthe comparison result of the comparison means when the minimumdistortion value is larger than the prescribed threshold value andwriting the added signal series to a video signal storing means, and anencoding control means is installed for performing variable lengthencoding of the position information of the block to provide the minimumdistortion and the quantization encoding output when the minimumdistortion value is larger than the prescribed threshold value andoutputting the variable length encoding signal to the transmission path.

The fifth object is achieved in that a first operation means isinstalled for estimating difference signal series between signal seriesof an input block in the last video signal inputted through means formaking a block and signal series of plural blocks read from a videosignal storing means by a reading means corresponding to the inputblock, a second operation means is installed for estimating the meanvalue and deviation component of the difference signal series per eachblock, a discrimination means is installed for discriminating the mostapproximate value to the input block on the basis of the mean value andthe deviation component of the difference signal series of each blockand outputting the position information and also comparing the meanvalue and the deviation component with the prescribed threshold valueand discriminating whether the input block is significant or not andoutputting the significance/insignificance information, a quantizationencoding means is installed for performing the quantization encoding ofthe difference signal series corresponding to the same position blockfrom the first operation block, a quantization decoding means isinstalled for decoding the quantization encoding output, a video signalreproduction means is installed wherein if the information issignificant the signal series by adding the difference signal seriesdecoded by the quantization decoding means to the signal series of thesame position block read by the reading means is written to a videosignal storing means and if the information is insignificant the signalseries of the most approximate block read by the reading means on thebasis of the position information is written thereto, and an encodingcontrol means is installed for inputting the quantization encodingoutput and the position information and the significance/insignificanceinformation and performing the variable length encoding of eachinformation except the position information if thesignificance/insignificance information is significant and except thequantization encoding output if it is insignificant and outputting thevariable length encoding signal to the transmission path.

The sixth object is achieved in that encoders are installed forcalculating distortion between each output vector index stored in avector code table and input signal vector and estimating the outputvector index to minimize the distortion, initial pseudo output vectorindex is inputted to the encoder of the initial stage among variousencoders so that code "0" of the required number is added to upper sideof the output vector index having shorter code length among the outputvector indexes of the encoding stages and indexes of the pseudo outputvector with equalized code length are not overlapped to each other, anda pair of output vectors corresponding to the pseudo output vector indexand the initial pseudo output vector index are constituted in equalizingat the vector code table of the encoder in each stage.

The eighth object is achieved in that input video signal series andvideo signal series being one frame period before the input video signalseries are made the prediction signal series and the difference betweenboth signal series is taken, the difference signal is compared with thethreshold value set by a feedback control signal from a transmissionbuffer and discrimination of significance/insignificance is performed,only the significant picture element is made a block and normalizedvector quantization encoding with means value separation is performedand also variable length encoding is performed to the block, and theencoded output signal is outputted through a transmission buffer to thetransmission path.

The ninth object is achieved in that an input buffer control meanscontrols read/write of an input buffer and the changing thereof on thebasis of a synchronizing signal of a camera and a changing signal of atransmission buffer and updates video data from the camera per frame andwrites the data and changes the read/write from the next frame afterchanging the transmission buffer, and in that an output buffer controlmeans controls the operation of an output buffer in accordance with asynchronizing signal of a monitor and a changing signal from the inputbuffer and causing the number of reading for the same frame in theoutput buffer to be in corresponding with the writing time for theformer frame in the receiving buffer.

BRIEF DESCRIPTION OF THE INVENTION

FIG. 1 is a diagram illustrating the whole constitution of a videoencoding apparatus in the prior art;

FIG. 2 is a diagram illustrating the general principle of vectorquantization;

FIGS. 3(A) and 3(B) illustrate the position relation between an inputblock in a video encoding apparatus and plural blocks as objects ofdistortion operation in the prior art;

FIG. 4 is a diagram illustrating the whole constitution of a videoencoding apparatus as a first embodiment of the invention;

FIG. 5 is a diagram illustrating the main part of the video encodingapparatus of a first embodiment of the invention;

FIG. 6 is a diagram illustrating an example of position relation betweenan input block controlled adaptably and plural blocks as objects ofdistortion operation in the first embodiment;

FIG. 7 is a diagram illustrating the constitution of a video encodingapparatus as background art of a second embodiment of the invention;

FIG. 8 is a diagram illustrating the constitution of a video encodingapparatus in a second embodiment;

FIG. 9 is a diagram illustrating constitution of a video encodingapparatus as background art of a third embodiment of the invention;

FIGS. 10(A) and 10(B) illustrate the position relation between an inputblock on a picture image and plural read blocks;

FIG. 11 is a block diagram illustrating the constitution of a videoencoding apparatus of the movement compensation type in the thirdembodiment;

FIGS. 12(A) and 12(B) illustrate the procedure of block formation ofinput signal series in the third embodiment;

FIG. 13 is a detailed constitution diagram of a distortion operationmember in the third embodiment;

FIG. 14 is a detailed constitution diagram of a quantization encodingmember in the third embodiment;

FIG. 15 is a diagram illustrating an example of variable length encodingcontrol in the third embodiment;

FIG. 16 is a block diagram of a video encoding apparatus of the movementcompensation type as background art of a fourth embodiment of theinvention;

FIGS. 17(A) and 17(B) illustrate the position relation between an inputblock and plural read blocks in FIG. 16;

FIG. 18 is a block diagram of a video encoding apparatus of the movementcompensation type in the fourth embodiment;

FIGS. 19(A) and 19(B) show the operation of a block constitution memberin the fourth embodiment;

FIG. 20 is a constitution diagram of a subtraction member in the fourthembodiment;

FIG. 21 is a constitution diagram of a mean/deviation operation memberin the fourth embodiment;

FIG. 22 is a block diagram illustrating constitution of a vectorquantization encoder as background art of a fifth embodiment of theinvention;

FIG. 23 is a block diagram illustrating the constitution of the fifthembodiment;

FIG. 24 is a block diagram illustrating the detailed constitution of themain elements in the fifth embodiment;

FIG. 25 is a constitution diagram illustrating an example of a treesearch vector quantization encoder as background art of a sixthembodiment of the invention;

FIG. 26 is a constitution diagram illustrating an example of the secondstage of a tree search vector quantization encoder as background art ofthe sixth embodiment;

FIG. 27 is a constitution diagram of a tree search vector quantizationencoder in the sixth embodiment;

FIG. 28 is a constitution diagram illustrating an example of the secondstage of a tree search vector quantization encoder in the sixthembodiment;

FIG. 29 is a diagram illustrating address map of output vector codetables #0, #1 in the sixth embodiment;

FIG. 30 is a diagram illustrating a search in the tree search vectorquantization in the sixth embodiment;

FIG. 31 is a block diagram of a vector quantization encoder betweenframes as background art of a seventh embodiment of the invention;

FIG. 32 is a block diagram of a vector quantization encoder betweenframes in the seventh embodiment;

FIG. 33 is a block diagram of a motion picture image transmissionapparatus as background art of an eighth embodiment of the invention;

FIG. 34 is a timing chart of the apparatus in FIG. 33;

FIG. 35 is a block diagram of a motion picture image transmissionapparatus in the eighth embodiment;

FIG. 36 is a timing chart in the eighth embodiment; and

FIG. 37 is a diagram illustrating a circuit for storing the receivingtime of frames in the apparatus shown in FIG. 35.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the invention will now be described. Before specificdescription of individual embodiments, an outline of the embodiment willbe generally described and then the constitution and operation will bedescribed.

In the embodiments, when a moving direction detecting means outputs adetecting signal, a movement information generator estimates thespecific position on a frame memory correspond to displacement amount ofa video camera calculated on the basis of the detecting signal andoutputs the specific position to a reference signal generator. Thereference signal generator reads plural blocks stored to the specificposition on the frame memory on the basis of the output from themovement information generator.

First Embodiment:

An embodiment of the invention will be described specifically referringto the accompanying drawings.

In FIG. 4, parts designated by numerals 1-3, 5-10 are similar to thosein FIG. 1, and the detailed description will be omitted. The videocamera 8 is provided with an angle sensor 26 which detects and outputsangular velocity in the oscillating motion when the video camera 8performs the oscillating motion only with respect to the x-axisdirection and the y-axis direction shown in FIG. 5.

Numeral 11 designates a movement information generator, and input sideof the movement information generator 11 is connected to the anglesensor 26 installed to the video camera 8 and output side thereof isconnected to the reference signal generator 4. As shown in FIG. 5, themovement information generator 11 is composed of v_(x) operation member22 and v_(y) operation member 23 which are connected at the input sideto the output side of the angle sensor 26, and of x-direction conversionmember 24 and y-direction conversion member 25 which are connected atthe output side to the input side of the reference signal generator 4.The v_(x) operation member 22 calculates the oscillating speed of thevideo camera 8 in the x-direction shown in FIG. 5 on the basis of anoutput signal from the angle sensor 26 and outputs the operation result.The v_(y) operation member 23 calculates the oscillating speed of thevideo camera 8 in the y-direction shown in FIG. 5 on the basis of anoutput signal from the angle sensor 26 and outputs the operation result.The x-direction conversion member 24 reads the operation data outputtedfrom the v_(x) operation member 22 and converts it into initialdeviation of picture element level in the x-direction and outputs theconverted data as movement information of the picture screen in thex-direction. The y-direction conversion member 25 reads the operationdata outputted from the v_(y) operation member 23 and converts it intoinitial deviation of picture element level in the y-direction andoutputs the converted data as movement information of the picture screenin the y-direction. The reference signal generator 4 takes the movementinformation and estimates the displacement amount of the video camera 8per one frame, and retrieves a block corresponding to the existing inputblock among plural blocks formed by signal series being one frame beforethe existing frame by shifting on the frame memory 3 by an amountcorresponding to the displacement amount of the video camera 8 andoutputs the retrieved block. FIG. 6 shows position relation between thecontrolled input block and plural blocks as objects of distortionoperation.

Operation in the above-mentioned constitution will be described.

Video signals outputted from the video camera 8 to the A/D converter 1are converted into digital signal series by the A/D converter 1 and thenoutputted to the block constituting member 2. In the block constitutingmember 2, every K picture elements close on the picture image are made ablock usually in rectangular form (or square form) on the picture image,and transformed in the arrangement and then outputted to the distortionoperation member 5 and the subtractor 6. On the other hand, the signalseries of the plural blocks, which are stored in the memory 3 and readby the reference sigal generator 4, are transmitted by the referencesignal generator 4 to the distortion operation member 5 insynchronization with the existing input signal series in a blockoutputted from the block constituting member 2.

The distortion calculation between the signal series of the existingblock and the signal series of the plural blocks being one frame beforethe existing frame is performed in the distortion operation member 5using, for example, Euclidean distortion or absolute distortion.According to the calculation results, the block to provide the minimumdistortion to the existing input block is selected among the pluralblocks. Assuming that the blocks as the calculation object are M innumber (M: integer not less than 2) and the block to provide the minimumdistortion is the l-th one among the M blocks (l=1, 2, . . . , M), thedistortion operation member 5 outputs the value of l and the signalseries of the block to the subtractor 6. The subtractor 6 estimates thedifference signal series between the signal series of the input blockand the signal series to give the minimum distortion and outputs thedifference signal series to the quantization encoding member 7. Thedifference signal series is subjected to quantization encoding in thequantization encoding member 7 and then outputted to the quantizationdecoding member 9. Both the difference signal series reproduced by thequantization decoding member 9 and the signal series of the blockoutputted from the distortion operation member 5 and giving the minimumdistortion are outputted to the adder 10 and added by the adder 10 andreproduced in the video signal. The video signal is written in the framememory 3 by the adder 10. The video signal inputted as above describedis made a block.

In the manner as described above, the inputted video signal is formed asa block which is used to select the block of most resembling those inthe former frame. The newest block is compared to the selected block,the difference or error component being quantized to form a coded outputsignal, together with information representing which block is the mostresembling one.

If the angle sensor 26 detects the oscillating motion of the videocamera 8 with respect to the x-direction and/or the y-direction shown inFIG. 5 and the detecting signal is inputted from the sensor 26 to thev_(x) operation member 22 and the v_(y) operation member 23, the v_(x)operation member 22 and the v_(x) operation member 23 calculate theoscillating speed in respective directions based on above-mentioned dataand output the oscillating speed to the x-direction conversion member 24and the y-direction conversion member 25. Thereby the x-directionconversion member 24 and the y-direction conversion member 25 performconversion to the initial deviation of the picture element level in thex-direction and the y-direction respectively, and output the converteddata as the movement information of the picture screen in thex-direction and the y-direction respectively. If the movementinformation of the picture screen is inputted in the x-direction and they-direction, the reference signal generator 4 operates the displacementamount of the video camera 8 per one frame as the vector quantity havingthe x-direction component and the y-direction component. Based on theoperation results, the reference signal generator 4 retrieves a blockcorresponding to the existing input block among the plural blocks whichare stored in the frame memory 3 and formed by the signal series beingone frame before the existing frame by shifting on the frame memory 3 asshown in FIG. 4. Thus absolute value of the block retrieved in thereference signal generator 4, i.e. the block to give the minimumdistortion on the frame memory 3 is represented by the movementinformation of the picture screen and the value of l.

According to the embodiment as above described, since the block to givethe minimum distortion is selected among the block group selectedadaptably on the basis of the movement information of the picturescreen, the approximation between the input block and the block to givethe minimum distortion becomes high and the difference signal is apt toconcentrate to a smaller value. Thereby the information amount generatedin the quantization encoding member 7 is considerably reduced. Althoughthe increase of the information amount by outputting the movementinformation of the picture screen must be considered in this case, themovement information outputted from the angle sensor 26 installed to thevideo camera 8 has the taking frequency of order of, for example, onceper several frames of the picture image or once per second and thereforethe converted information amount per one picture screen becomes small.Accordingly, the information reduction amount of the quantizationencoding output appears almost entirely as the information compressioneffect.

Second Emobodiment:

A second embodiment of the invention will now be described. Beforedescribing the second embodiment, background art as the basis of thesecond embodiment will be described.

FIG. 7 shows a video encoding apparatus in background art. In FIG. 7,numeral 8 designates a plurality of cameras for inputting pictureimages, and numeral 200 designates a changing device for changing theplural video signals. Numeral 100 designates a video encoding apparatuscomprising an A/D converter 1 for converting the inputted video signalsin A/D conversion, a pre-processor 40 for performing pre-processing toencode the video signals in digital form, a frame memory 3 for storingthe video signal being one frame before the existing frame, a subtractor6 for estimating the difference between the output of the pre-processor40 and the output of the frame memory 3, a quantization encoding member7 for performing quantization encoding of the difference signal betweenframes, a quantization decoding member 9 for performing the reverseprocessing to the quantization encoding member 7, and an adder 10.

Among the video signals outputted from the plural cameras 8, only one isselected by the selecting device 200 and outputted. If the output signalis inputted to the video encoding apparatus 100, the signal is convertedin the A/D conversion by the A/D converter 1 and processed in thepre-processor for encoding by the pre-processor 40 and then inputted tothe subtractor 6 so as to estimate the difference signal between frames.The difference signal between frames is subjected to the quantizationencoding in the quantization encoding member 7, and then outputted tothe outside and also subjected to the quantization decoding in thequantization decoding member 9. For processing of the next frame. thedecoded signal is added through the adder 10 to output of the framememory 3 and then stored in the frame memory 3.

An example of a practical use of the video encoding apparatus is ateleconferencing system or the like. In the teleconferencing system, aplurality of cameras are often used and signals are suitably changed.Studying the operation when the changing device 200 is changed, outputvideo signals of the changing device 200 become discontinuous just afterthe changing and synchronizing signal or the like may be significantlyfluctuated. As a result, the prior art has problems in that theinsignificant difference signal between frames is encoded untilsynchronized drawing finishing and the encoding picture image isfluctuated. In order to eliminate the fluctuation of the synchronoussignal, the plural cameras 8 may be synchronously coupled. However, thesynchronous coupling of cameras is usually possible only in expensivecameras.

An outline of the second embodiment will be described.

In the second embodiment, a fluctuation detecting means detectsfluctuation of the synchronous signal due to changing of input videosignals and stops operation of a quantization encoding member so as toprevent the fluctuation of the picture image due to encoding of thesignificant difference signal between frames.

The second embodiment will be described specifically.

In FIG. 8, parts similar to those in FIG. 7 are designated by the samereference numerals. Numeral 7 designates a quantization encoding memberwhich can be ON/OFF controlled by external signals, numeral 9 aquantization decoding member which performs the reverse processing tothe quantization encoding member 7, numeral 110 a detector whichseparates the synchronous signal from the inputted video signals anddetects the time variation and controls the quantization encoding member7 and changing means as hereinafter described, numeral 120 a changingdevice which changes the output of the pre-processor 40 and the outputof the subtractor 6 according to the output of the detector 110, andnumeral 130 a changing device which changes the ON/OFF state of theoutput of the frame memory 3 inputted to the adder 10. The changingdevices 120, 130 are set to restore the output of the detector 110 afterbeing lost to the original state with a delay corresponding to one frameof the video signal. In this case, the detector 110 constitutes afluctuation detecting means and the changing device 120 constitutes asignal changing means.

Operation of the second embodiment will be described.

The plural cameras 8 are not synchronously coupled but individuallytransmit the video signals to the changing device 200. The video signalsinputted through the changing device 200 to the video encoding device100 are converted in A/D conversion by the A/D converter 1, and thenprocessed in pre-processing by the pre-processor 40 and also inputted tothe detector 110 so as to perform synchronous signal separation andphase difference detection. The video signal after finishing thepre-processing is converted into the difference signal between frames tothat being one frame before the frame memory 3 by the subtractor 6, andthe difference signal is inputted to the changing device 120. Both thedifference signal between frames and the original video signal areinputted to the changing device 120, but the difference signal betweenframes is usually outputted from the changing device 120 as shown inFIG. 8. The difference signal between frames outputted from the changingdevice 120 is subjected to the quantization encoding by the quantizationencoding member 7, and then outputted to the outside and also subjectedto the quantization decoding by the quantization decoding member 9. Onthe other hand, in the changing device 130, since output of the framememory 3 is usually outputted without changing, the difference signalbetween frames subjected to the quantization decoding and outputted bythe quantization decoding member 9 is added in the added 10 to the framememory output outputted from the changing device 130, and the addedoutput is written to the frame memory 3 to provide for processing forthe of next frame.

Studying the operation when the changing device 200 for changing thecameras 8 is changed, since the output video signal becomesdiscontinuous just after the changing, the detector 110 detects thesignificant phase shift in synchronous signal. If the detector 110detects the phase shift, the quantization encoding member 7 stops theencoding of the picture image and prevents the fluctuation of thepicture image. At the same time, the changing device 120 for input ofthe quantization encoder 7 is changed to output the original videosignal, and also the changing device 130 for input of the adder 10 ischanged so that the output of the frame memory 3 is not supplied to theadder 10. If the apparatus finishes redrawing of the synchronous signal,output of the detector 110 is lost and the quantization encoding member7 starts encoding of the original video signal. Then, output of thequantization decoding member 9 is written without changing to the framememory 3. When encoding of the original video signal corresponding toone frame is finished, the changing devices 120, 130 are reset to thenormal state and the original encoding of the difference signal betweenframes is started.

The above-mentioned operation of the second embodiment is compared withthat of FIG. 7 as follows:

(i) Since time fluctuation of the synchronous signal is detected justafter changing of the changing device 120 and operation of thequantization encoding member 7 is stopped, irregularity of the pictureimage due to encoding of the insignificant difference signal betweenframes is eliminated.

(ii) Only just after detecting the finishing of re-drawing of thesynchronous signal, not the difference signal between frames but theoriginal video signal is encoded. Consequently, restoring to theoriginal picture image is rapid in comparison to the case that thedifference signal between frames is used without changing. Although thepicture image becomes irregular at changing the changing device 120 andis restored slowly in the prior art, the picture image stands still justafter the changing and is restored rapidly in the embodiment.

Third Embodiment:

Before describing a third embodiment of the invention specifically,background art as the basis of the third embodiment will be described.

FIG. 9 is a block diagram illustrating constitution of a video encodingapparatus of movement compensation type as background art of the thirdembodiment as hereinafter described. In FIG. 9, similar parts to thosein FIG. 1-FIG. 8 are designated by the same reference numerals. Numeral80 designates an encoding control member which converts positioninformation of a block giving the minimum distortion and quantizationencoding output in variable length encoding and outputs the variablelength encoding output to a transmission path T, numeral 9 aquantization decoding member which reproduces difference signal seriesfrom the quantization encoding signals, and numeral 10 an adder whichadds the quantization decoding output to the signal series of the blockgiving the minimum distortion and reproduces the video signal and writesit in a frame memory 3.

Operation of the prior art will be described. Analog video signals areinputted to an A/D converter 1 and converted into digital signal series.The signal series is made a block per every K elements close on thepicture image by a block constituting member 2, and arrangement of thesignal series is converted and then each block is outputted. The blockis usually constituted in rectangular form (or square form) on thepicture image. On the other hand, the video signal being one framebefore the existing input signal is stored in the fram memory 3, and thesignal series of plural blocks including a block at the same position asthe existing input block on the picture image is synchronized with theinput signal series by a reference signal generator 4, and then read andtransmitted to a distortion operation member 5. FIG. 10 shows an exampleof position relation between the existing input block A (FIG. 10(A)) andthe plural read blocks Ma including the block a at the same position asthe existing block A (FIG. 10(B)) in this case. The distortion operationmember 5 calculates distortion between the signal series of the inputblock and the signal series of the plural blocks from the frame memory3. The distortion calculation is performed using, for example, Euclideandistortion or absolute value distortion. According to the calculationresults, the block to provide the minimum distortion to the input blockis selected. Assuming that the blocks as the calculation object are M innumber (M: integer not less than 2) and the block to provide the minimumdistortion is the l-th one among the M blocks (l=1, 2, . . . , M), thedistortion operation member 5 outputs the value of l and the signalseries of the block. A subtractor 6 outputs the difference signal seriesbetween the input signal series and the signal series to give theminimum distortion. The quantization encoding member 7 performs thequantization encoding of the difference signal series. Both thequantization encoding signal and the value l as position information aretransmitted to the encoding control member 80, and subjected to thevariable length encoding and further transmitted to the actualtransmission path T. The difference signal series decoded by thequantization decoding member 9 and the signal series of the blockoutputted from the distortion operation member 5 and giving the minimumdistortion are added by the adder 10, and the added output is reproducedas the video signal and written in the frame memory 3.

In the manner as described above, the inputted video signal is formed asa block which is used to select the block most resembling those in theformer frame. The newest block is compared to the selected block, thedifference or error component being quantized to form a coded outputsignal, together with information representing which block is the mostresembling one.

The video encoding apparatus in the prior art is constituted as abovedescribed. Even if a block of very high approximation exists as a resultof the distortion operation, the quantization encoding is performed tothe difference signal series unconditionally, thereby the amount ofunrequired information may be increased. Moreover, the difference signalseries including the quantization error is added to the block having thehigh approximation really; thereby the quantization error may be storedand the distortion of the picture image may be enlarged.

The outline of the third embodiment will now be described.

In the third embodiment, the value of the minimum distortion from adistortion operation means is compared with a prescribed threshold valueby a comparison means. Only when the value of the minumum distortion islarger than the prescribed threshold value, position information of ablock outputted from the distortion operation means and giving theminimum distortion and quantization encoding output of difference signalseries are converted in variable length encoding by an encoding controlmeans, and the variable length encoding signal is outputted to atransmission path. The difference signal series reproduced from thequantization encoding output is added to the signal series of the blockgiving the minimum distortion, and the added output is written in avideo signal storing means by a writing means.

The third embodiment will be described specifically referring to FIGS.11 through 15.

In FIGS. 11 through 15, similar parts to those in FIGS. 1 through 10 aredesignated by the same reference numerals. Numeral 5 designates adistortion operation member as distortion operation means which operatesdistortion between signal series of the input block and signal series ofplural blocks, and outputs position information of a block giving theminimum distortion and the value of the distortion and the signalseries, numeral 60 a comparator as comparing means which compares thevalue of the minimum distortion outputted from the distortion operationmember 5 with the prescribed threshold value and outputs the comparisonresults, numeral 80 an encoding control member as encoding control meanswhich converts the position information of the block giving the minimumdistortion and the quantization encoding output in variable lengthencoding under control of output of the comparator 60, and outputs thevariable length encoding signal to the transmission path T, and numeral10 an adder as writing means which adds the quantization decoding output(difference signal series) to the signal series of the block giving theminimum distortion under control of output of the comparator 60, andwrites the added output in the frame memory 3.

Operation of the third embodiment will be described in detail. Analogvideo signals are inputted and converted into digital signal series bythe A/D converter 1, and further made a block per every K elements closeon the picture image by the block constituting member 2. FIG. 12 showsan example of a state in the arrangement conversion of the signal seriesby the block formation. FIG. 12 shows the order of the signal series inarrow, wherein FIG. 12(A) shows state before the block formation andFIG. 12(B) shows state after the block formation. Symbol A designates ablock in the block formation. On the other hand, a video signal beingone frame before the existing input signal is stored in the frame memory3, and the signal series of the plural blocks including the block at thesame position as the existing input block on the picture image issynchronized with the input signal series by the reference signalgenerator 4 and then read from the frame memory 3 and transmitted to thedistortion operation member 5.

FIG. 13 shows a detailed constitution example of the distortionoperation member 5. In FIG. 13, numeral 51 designates distortionoperation circuits, and numeral 52 designates a comparator whichcompares the operation results of the distortion operation circuits 51.The input signal series and the signal series of one block among outputsof the reference signal generator 4 are synchronized and inputted to thedistortion operation circuits 51. Each distortion operation circuit 51performs a prescribed distortion operation (for example, Euclideandistortion or absolute value distortion), and outputs three sorts ofsignals, i.e., the value of the distortion, the position information ofthe inputted reference signal block and the signal series, to thecomparator 52 at the rearward stage. The comparator 52 compares thevalues of the distortion inputted from the distortion operation circuits51 and selects the minimum value and outputs three sorts of signals,i.e., the distortion value, the position information of the referencesignal block and the signal series. The signal series of the blockoutputted in this manner and giving the minimum distortion is inputtedto the subtractor 6 shown in FIG. 11, and the difference signal seriesbetween the signal series of the block giving the minimum distortion andthe input signal series inputted without passing through the distortionoperation member 5 is outputted. In the processing hitherto, theinformation that the input signal series in block formation resemblesmost closely to which block in the picture image being one frame beforethe existing input signal and the difference signal series to the blockcan be obtained.

The difference signal series outputted from the subtractor 6 issubjected to the quantization encoding in the quantization encodingmember 7; thereby the information amount is compressed. Various methodsfor the quantization encoding have been proposed, and adaptation typevector quantizatin is used in the embodiment. Detail of the adaptationtype vector quantization is disclosed in "Murakami et al: AdaptationType Vector Quantization System-Quantization between Frames, TechnicalReport of the Institute of Electronics and Communication Engineers ofJapan, IE84-1". The principle of the vector quantization will now bebriefly described.

The difference signal series of K in number are brought together intoinput vector x=x1, x2, . . . , xK. then, the K-dimensional Euclideansignal space Rk (X E Rk) has the representative points of N in number(called output vector) yi=yi1, yi2, . . . , yik, and set of therepresentative points is made Y=y1, y2, . . . , YN. If each partition ofRk having output vector yi as the representative point (e.g., center ofgravity) is made R1, R2, . . . , RN and index set of yi is made I={1, 2,. . . , N}, vector quantization Q is expressed as cascade connection ofencoding C and decoding D.

    Q(x)=yi if xERi

    C:x→i if d(x, yi)<d(x, yi) for  j

    D:i→yi

If distortion d (x, yi) represents distance between input/output vectorand is defined by absolute value distortion, it follows that ##EQU2##

The adaptation type vector quantization performs normalization to theinput vector x. That is, conversion is performed as follows: ##EQU3##Vector S=S₁, S₂, . . . , S_(k) obtained in the conversion is used asinput vector in the adaptation type vector quantization. Consequently,the difference signal series of K in number can be quantized into threevalues i. m, σ.

FIG. 14 shows a detailed constitution example of the quantizationencoding member 7 in FIG. 11. In FIG. 14, numeral 71 designates anoperation member of mean value m of difference signal series x, numeral72 an operation member of variance σ, numeral 73 a normalizing memberwhich converts the difference signal series x into S using the operationresults m, σ, numeral 74 a descrimination member which performsdiscrimination under prescribed condition using the operation results m,σ and the prescribed threshold value, numeral 75 a vector storage memberwhich stores plural output vectors, and numeral 76 a distortionoperation member which performs a distortion operation between thenormalized difference signal series S and the output vector group of thevector storage member 75 and outputs the index i of the output vectorhaving the minimum distortion. Operation of the quantization encodingmember 7 will be described. The difference signal series x is inputtedto the mean value operation member 71 where the mean value m isoperated. The operation results and the difference signal series x areinputted to the variance operation member 72 where the variance σ isoperated. The mean value m, the variance σ and the difference signalseries x are inputted to the normalizing member 73 which converts thedifference signal series x into S 1/σ (x-m) and outputs the signalseries S. The signal series S is inputted to the distortion operationmember 76, and the distortion operation between the signal series S andthe output vector group in the vector storage member 75 is performed,and then the quantization is performed into the index i of the outputvector having the minimum distortion. On the other hand, the mean valuem and the variance σ are inputted to the discrimination member 74, andthe discrimination is effected under prescribed condition regardingwhether the existing difference signal series x is significant or not,that is, whether the signal series x has sufficient information to beencoded, and then the discrimination results, the mean value m and thevariance σ are outputted. In above-mentioned operation, the differencesignal series x is subjected to the quantization encoding in the meanvalue m, the variance σ, the index i and the results ofsignificance/insignificance discrimination.

The description is performed again referring to FIG. 11. In FIG. 11, thevalue of the minimum distortion outputted by the distortion operationmember 5 is transmitted to the comparator 60. the comparator 60 comparesthe value of the minimum distortion with the prescribed threshold value,and information regarding whether the value of the minimum distortion isless than or more than the threshold value is transmitted to theencoding control member 80 and the adder 10. The information representsa criterion whether the input signal series and the signal series of theblock giving the minimum distortion closely resemble each other. Whenthe signal series of the block giving the minimum distortion resemblesthe input signal series well, the picture image of excellent quality canbe reproduced even if the difference signal series as output of thesubtractor 6 is not encoded.

In the encoding control member 80, the position information l of theblock giving the minimum distortion as output of the distortionoperation member 5, the mean value m as output of the quantizationencoding member 7, the variance σ, the index i and results of thesignificance/insignificance discrimination, that is, five sorts ofinformation, are considered together with output of the comparator 60and codes are assigned and the variable length encoding as a whole isperformed. FIG. 15 shows an example of control condition in this case.It is understood from FIG. 15 that output of the comparator 60 in FIG.11 assigns codes to all of the position information l, thesignificance/insignificance information, the index i, the mean value mand the variance σ only when the minimum distortion ≧ the threshold andthe significance/insignificance information is significant, and that thecomparator 60 assigns codes to only the position information l and thesignificance/insignificance information under other conditions.Consequently, this becomes the variable length code having the leastlength. In the apparatus of the prior art, since codes are assigned toall of the position information l, the significance/insignificanceinformation, the index i, the mean value m and the variance σ even whenthe minimum distortion < the threshold and thesignificance/insignificance information is significant, unrequiredinformation in the video reproduction is generated excessively.

Various sorts of the information of i, m, σ, significance/insignificanceoutputted from the quantization encoding member 7 in FIG. 11 are alsoinputted to the quantization decoding member 9, and the differencesignal series is decoded. The quantization decoding member 9 is providedat inside with a vector storage member in similar constitution to thatof the quantization encoding member 7; thereby the output vector y_(i)is decoded from the inputted index i. Further, using the mean value mand the variance σ, conversion is performed in that ##EQU4## thereby thevector x is decoded. The vector x obtained in this manner is added asthe difference signal series by the adder 10 to the signal series of theblock giving the minimum distortion as output of the distortionoperation member 5. If the minimum distortion < the threshold value,i.e., if the signal series of the block giving the minimum distortionresembles the input signal series well, output of the quantizationdecoding member 9, i.e., the reproduced difference signal series isignored, and output of the comparator 60 is controlled so that thesignal series of the block giving the minimum distortion as output ofthe distortion operation member 5 is outputted without changing. In thisconstitution, the difference signal series including the quantizationerror by passing through the quantization encoding member 7 and thequantization decoding member 9 is prevented from being added to thesignal series having high approximation, thus adding of excessivedistortion to the reproduced picture image can be avoided. Output of theadder 10 is written to the frame memory 3 and is ready for the inputsignal of the next frame. Although the adaptation type vectorquantization encoding is adopted as quantization encoding method in theembodiment, the invention has similar effects in the case such as vectorquantization where the block encoding is not used.

According to the embodiment as above described, the video encodingapparatus comprises a distortion operation means which operatesdistortion between signal series of an input block in the last videosignal inputted through a block constituting means and signal series ofplural blocks read from a video signal storage means corresponding tothe input block by a reading means and outputs the minimum distortionand the position information of the block giving the minimum distortionand the signal series, a comparison means which comprises the value ofthe minimum distortion with the prescribed threshold value, aquantization encoding means which performs quantization encoding of thedifference signal series between the signal series of the input blockand the signal series of the block giving the minimum distortion, awriting means which adds the difference signal series reproduced fromthe quantization encoding output through the quantization decoding meansto the signal series of the block giving the minimum distortion when thevalue of the minimum distortion is larger than the prescribed thresholdvalue based on the comparison results of the comparison means and writesthe added output to the video signal storage means, and an encodingcontrol means which performs variable length encoding of the positioninformation of the block giving the minimum distortion and thequantization encoding output when the minimum distortion is larger thanthe threshold value and outputs the variable length encoding output tothe transmission path. Accordingly, excessive information generating andstorage of the quantization error can be eliminated.

Fourth Embodiment:

Before describing a fourth embodiment of the invention specifically,background art as the basis of the fourth embodiment will be describedreferring to FIGS. 16 and 17.

In FIGS. 16 and 17, similar parts to those in FIGS. 1 through 15 aredesignated by the same reference numerals. Numeral 117 designates anoperation member which provides mean value and deviation componentwithin a block of difference signal series, numeral 118 a discriminationmember which compares the mean value and the deviation component withthe prescribed threshold value and obtains significance/insignificanceinformation that information is insignificant if both the mean value andthe deviation component are less than the threshold value and it issignificant under other conditions, numeral 119 a normalizing memberwhich performs d.c. separation normalizing of the difference signalseries using the mean value and the deviation component, numeral 7 aquantization encoding member which performs quantization encoding ofoutput of the normalizing member 119, numeral 80 on encoding controlmember which converts position information of a block giving the minimumdistortion, significance/insignificance information, quantizationencoding output, mean value and deviation component in variable lengthencoding and outputs the variable length encoding output to atransmission path T, numeral 9 a quantization decoding member whichdecodes the quantization encoding a signal, numeral 113 a differencesignal reproduction member which applies mean value adding and weightingto the quantization decoding output using the mean value and thedeviation component and reproduces the difference signal series, andnumeral 114 an adder which adds output of the difference signalreproduction member 113 to the signal series of the block giving theminimum distortion and reproduces the video signal and writes it to aframe memory 3.

Operation of the prior art will be described. Analog video signals areinputted to an A/D converter 1 and converted into digital signal series.The signal series is made a block per every K elements close on thepicture image by a block constituting member 2, and arrangement of thesignal series is converted and then each block is outputted. The blockis usually constituted in rectangular form (or square form) on thepicture image. On the other hand, video signal being one frame beforethe existing input signal is stored in the frame memory 3, and signalseries of plural blocks including a block at the same position as theexisting input block on the picture image is synchronized with the inputsignal series by a reference signal generator 4, and then read andtransmitted to a distortion operation member 5. FIG. 17 shows an exampleof position relation between the existing input block A (FIG. 17(A)) andthe plural read blocks Ma including the block a at the same position asthe existing block A on the picture image (FIG. 17(B)) in this case. Thedistortion operation member 5 calculates distortion between the signalseries of the input block and the signal series of the plural blocksfrom the frame memory 3. The distortion calculation is performed using,for example, Euclidean distortion or absolute value distortion.According to the calculation results, the block to provide the minimumdistortion to the input block is selected. Assuming that the blocks ofthe calculation object are M in number (M: integer not less than 2) andthe block to provide the minimum distortion is the l-th one among the Mblocks (l=1, 2, . . . , M), the distortion operation member 5 outputsthe value of l and the signal series of the block. A subtractor 6outputs the difference signal series between the input signal series andthe signal series to give the minimum distortion. The meanvalue/deviation operation member 117 operates the mean value and thedeviation within the block of the difference signal series. Thediscrimination member 118 has prescribed threshold values Th₁ and Th₂ tothe mean value and the deviation respectively, and performsdiscrimination in that

If mean value <Th₁ and deviation <Th₂ significance/insignificanceinformation→insignificant

If mean value ≧Th₁ or deviation ≧Th₂ significance/insignificanceinformation→significant

The normalizing member 119 subtracts the mean value from each signal ofthe difference signal series and performs division by the deviation;thereby the normalized difference signal series is obtained.

The quantization encoding member 7 performs the quantization encoding ofthe normalized difference signal series. The quantization encodingsignal, the mean value, the deviation, the significance/insignificanceinformation and the position information l of the block giving theminimum distortion are transmitted to the encoding control member 80,and subjected to the variable length encoding and further transmitted tothe actual transmission path T.

If the significance/insignificance information is significant, all sortsof information inputted to the encoding control member 80 are subjectedto the variable length encoding. However, if it is insignificant, onlythe significance/insignificance information and the position informationl are subjected to the variable length encoding and outputted so as toreduce the amount of information generated.

The normalized difference signal series decoded by the quantizationdecoding member 9 is subjected to multplication of the deviation andaddition of the mean value by the difference signal reproduction member113 and thereby reproduced as the difference signal series. However, ifthe significance/insignificance is insignificant, the difference signalseries entirely becomes 0. The difference signal is added to the signalseries of the block giving the minimum distortion by the adder 114, andthe adding output is reproduced as the video signal and written in theframe memory 3.

In the manner as described above, the inputted video signal is formed asa block which is used to select the block most resembling those in theformer frame. The newest block is compared to the selected block, thedifference or error component being quantized to form a coded outputsignal, together with information representing which block is the mostresembling one.

The video encoding apparatus in the prior art is constituted as abovedescribed. Property of the inputted video signal becomes significantwhen the reference block at the same position on the picture image isused. If the appearing frequency of the blocks being insignificantbecomes high by using the plural reference blocks, the video encodingapparatus is effective to reduce the information amount. However, if theappearing frequency of the blocks being significant becomes high byusing the plural reference blocks, the information amount may beincreased by the position information of the reference blocks.

Outline of the fourth embodiment will now be described.

In the fourth embodiment, in order to discriminate approximation betweenplural reference blocks and an input block, mean value and deviationcomponent of difference signal series are used although these are usedonly to discriminate whether information is significant or not in theprior art. Thus the discrimination means discriminate not only thesignificance/insignificance information but also the approximation. Ifinformation does not become insignificant even at a block of the highestapproximation, difference signal series between the input block and ablock at the same position as the input block is subjected toquantization encoding, and position information of the reference blocksneed not be transmitted by using the quantization encoding output.

The fourth embodiment will be described specifically referring to FIGS.18 through 21.

In FIGS. 18 through 21, similar parts to those in FIGS. 1 through 17 aredesignated by the same reference numerals. Numeral 150 designates asubtractor as first operation means which outputs difference signalseries between signal series of an input block and signal series ofplural blocks, numeral 160 a mean value/deviation operation member assecond operation means which operates mean value and deviation componentwithin each block of the plural difference signal series, numeral 170 adiscrimination member as discrimination means which selects a blockhaving the highest approximation to signal series of the input block(most approximate block) from the mean value and the deviation componentof each block based on prescribed procedure and outputs the positioninformation and also compares the mean value and the deviation componentof the most approximate block with the prescribed threshold value anddiscrimination whether the input block is significant or not and outputsthe significance/insignificance information, numeral 119 a normalizingmember which performs d.c. separation normalizing to difference signalseries corresponding to a same position block using output of thesubtractor 150 corresponding to a block at the same position as theinput block on the picture image (same position block) and output of themean value/deviation operation member 160 corresponding to the sameposition block, numeral 80 an encoding control member as encodingcontrol means which converts quantization encoding output of aquantization encoding member 7, the mean value and the deviationcomponent of the same position block outputted from the meanvalue/deviation operation member 160 and the position information andthe significance/insignificance information of the most approximateblock outputted from the discrimination member 170 into variable lengthencoding and outputs the variable length encoding signal, numeral 9 aquantization decoding member as quantization decoding means whichdecodes the quantization encoding output, numeral 113 a differencesignal reproduction member which applies mean value adding and weightingto the quantization decoding output using the mean value and thedeviation component and reproduces the difference signal seriescorresponding to the same position block, and numeral 180 a video signalreproduction member as video signal reproduction means which writes thereference signal series corresponding to the same position block amongoutputs of the reference signal generator 4 added to the reproduceddifference signal series corresponding to the same position block or thereference signal series itself corresponding to the most approximateblock shown by the position information among outputs of the referencesignal generator 4 to the frame memory 3 under control of thesignificance/insignificance information.

Operation of the fourth embodiment will be described in detail. Analogvideo signals are inputted and converted into digital signal series bythe A/D converter 1, and further made a block per every K elements closeon the picture image by the block constituting member 2. FIG. 19 showsan example of a state in the arrangement conversion of the signal seriesby the block formation. FIG. 19 shows the order of the signal series inarrow, and FIG. 19(a) shows state before the block formation and FIG.19(b) shows state after the block formation. Symbol A designates a blockin the block formation. On the other hand, video signal being one framebefore the existing input signal is stored in the frame memory 3, andthe signal series of the plural blocks including the block at the sameposition as the existing input block on the picture image issynchronized with the input signal series by the reference signalgenerator 4 and then read from the frame memory 3 and transmitted to thesubtractor 150.

FIG. 20 shows a detailed constitution example of the subtractor 150. InFIG. 20, the input signal series and the reference signal series of theplural blocks are synchronized and inputted to each subtractor therebythe difference signal series corresponding to each reference block canbe obtained. The reference signal series of the plural blocks includethe reference signal series of the same position block, and thedifference signal series corresponding to this is transmitted to themean value/deviation operation member 160 and also to the normalizingmember 119 shown in FIG. 18 in similar manner to other reference blocks.

FIG. 21 shows a detailed constitution example of the meanvalue/deviation operation member 160. In FIG. 21, numeral 161 designatesan accumulator which accumulates the inputted signal series within theblock, numeral 162 a divider which divides the inputted signals by thenumber K of elements within the block, numeral 164 a subtractor whichperforms subtraction of ε_(i) ^(n) -m^(n), and numeral 163 a calculatorwhich performs absolute value calculation. Assume that the referenceblocks are M in number (M: integer not less than 2) and the differencesignal series corresponding to the M blocks are represented by ε⁰, ε¹, .. . , ε^(n), . . . , ε^(M-1) respectively. Wherein, ε⁰ is the differencesignal series corresponding to the same position block.

The mean value/deviation operation member 160 performs followingoperation to the difference signal series ε^(n) =(ε₁.sup.η, ε₂.sup.η, .. . , ε_(k).sup.η) thereby the mean value m^(n) and the deviationcomponent σ^(n) can be obtained. ##EQU5## The mean value m^(n) and thedeviation component σ^(n) corresponding to each reference blockoutputted from the mean value/deviation operation member 160 aretransmitted to the discrimination member 170 where the most approximateblock is selected and the significance/insignificance discrimination ofthe block is performed.

The object of the selection of the most approximate block is that thesignificance/insignificance information finally becomes insignificant.Consequently, the following procedure is used as the method of selectingthe most approximate block.

(i) Among inputted M blocks of (m^(n), σ^(n)), select one block tosatisfy that m^(n) <Th₁ and σ^(n) <Th₂. Wherein, Th₁ and Th₂ arethreshold values for the significance/insignificance discrimination.

(ii) If there is no block to satisfy the condition, thesignificance/insignificance information is deemed as significant andoutputted.

(iii) If there is any block to satisfy the condition, thesignificance/insignificance information is deemed as insignificant andoutputted. In order to select the most approximate block among pluralblocks to satisfy the condition, an estimation function is set ashereinafter described.

    γn=α|m.sup.n |+βσ.sup.n (α, β: constant)

A block corresponding to (m^(n), σ^(n)) to minimize γ is made the mostapproximate block. If γl at n=l (l: any integer among 1-M) becomesminimum, l is deemed as the position information of the most approximateblock and outputted.

Operation is further described in the case of significance andinsignificance of information.

(a) In the case of insignificance

Only the significance/insignificance information and the positioninformation of the most approximate block are converted in variablelength encoding by the encoding control member 80 and transmitted to thetransmission path T. In the video signal reproduction member 180, thereference signal series of the most approximate block shown by theposition information from the reference signal generator 4 is read andwritten in the frame memory 3 and is ready for inputting of the videosignal to next frame.

(b) In the case of significance

In the case of significance, the most approximate block is not used butthe same position information becomes the object. Among the differencesignal series outputted from the subtractor 150, ε⁰ corresponding to thesame position block and m⁰, σ⁰ outputted from the mean value/deviationoperation member 160 are inputted to the normalizing member 119, wherefollowing operation is performed to ε⁰ thereby the normalized signalseries x⁰ is obtained. ##EQU6## Signal x⁰ obtained in this manner istransmitted to the quantization encoding member 7 and the informationamount is compressed. In the embodiment, vector quantization is used inthe quantization encoding member 7.

The vector quantization will now be briefly described. The input signalseries of K in number are brought together into input vector x={x₁, x₂,. . . , x_(K) }. Then, the K-dimensional Euclidean signal space R^(k) (xE R^(k)) has the representative points of N in number (called outputvector) y_(i) ={y_(i1), y_(i2), . . . , y_(ik) }, and set of therepresentative points is made Y={y₁, y₂, . . . , y_(N) }. If eachpartition of R^(k) having output vector y_(i) as the representativepoint (e.g., center of gravity) is made R₁, R₂, . . . , R_(N) and indexset of y_(i) is made I={1, 2, . . . , N}, vector quantization Q isexpressed as cascade connection of encoding C and decoding D as follows:

    Q=(x)=y.sub.i if xεR.sub.i

    C:x→i

    if d (x, y.sub.i)<d (x, y.sub.i)

    for  j

    D:i→y.sub.i

If distortion d (x, y_(i)) represents distance between input/outputvector and is defined by absolute value distortion, it follows that##EQU7##

The signal series x⁰ inputted to the quantization encoding member 7 bythe vector quantization encoding is converted in quantization encodingto the index I and outputted.

In the encoding control member 80, the significance/insignificanceinformation, the mean value estimated using the same position block asthe reference signal, the deviation component and the quantizationencoding output, that is, four sorts of signals, are converted invariable length encoding and outputted to the transmission path. In thiscase, the position information of the most approximate block becomesunnecessary.

In the quantization decoding member 9, the index I outputted from thequantization encoding member 7 is converted in vector quantizationdecoding thereby the signal series y⁰ ={y₁ ⁰, y₂ ⁰, . . . , y_(k) ⁰ } isobtained. In the difference signal reproduction member 113, operation ofmean value adding and weighting

    ε.sup.0 =σ.sup.0 y.sup.0 +m.sup.0

is performed, and the difference signal series corresponding to the sameposition block is reproduced and outputted. In the video signalreproduction member 180, the reference signal series of the sameposition block is read from the reference signal generator 4, and thedifference signal series reproduced by the difference signalreproduction member 113 is added thereto, and the added output iswritten in the frame memory and is ready for the video signal in nextframe.

According to the embodiment as above described, the video encodingapparatus comprises a first operation means which operates thedifference signal series between signal series of an input block in thelast video signal inputted through a block constituting means and signalseries of plural blocks read from a video signal storage meanscorresponding to the input block by a reading block, a second operationmeans which operates a mean value and deviation component of thedifference signal series per each block, a discrimination means whichdiscriminates the most approximate block having the highestapproximation to the input block from the mean value and the deviationcomponent of the difference signal series of each block and outputs theposition information and also compares the mean value and the deviationcomponent with the prescribed threshold value and discriminates whetherthe input block is significant or not and outputs thesignificance/insignificance information, a quantization encoding meanswhich performs quantization encoding of the difference signal seriescorresponding to the same position block from the first operation means,a quantization decoding means which decodes the quantization encodingoutput, a video signal reproduction means which writes the referencesignal series decoded by the quantization decoding means and added tothe signal series of the same position block read by the reading meansto the video signal storage means if the significance/insignificanceinformation is significant and also writes the signal series of the mostapproximate block read by the reading means on the basis of the positioninformation to the video signal storage means if thesignificance/insignificance information is insignificant, and anencoding control means which inputs the quantization encoding output andthe position information and the significance/insignificance informationand performs the variable length encoding to the inputted signals exceptthe position information if the significance/insignificance informationis significant and to the inputted signals except the quantizationencoding output if the significance/insignificance information isinsignificant and then transmits the variable length encoding output tothe transmission path. Accordingly, when the significance/insignificanceinformation is significant, the same position block corresponding to theinput block is used and the position information becomes unnecessary;thereby increase of the information amount can be suppressed even whenmany significant input blocks exist due to the property of the picturescreen.

Fifth Embodiment:

Before describing a fifth embodiment of the invention specifically,background art as the basis of the fifth embodiment will be describedreferring to FIG. 22.

FIG. 22 is a block diagram illustrating constitution of a vectorquantization encoder as background art of the fifth embodiment. In FIG.22, similar parts to those in FIGS. 1 through 21 are designated by thesame reference numerals. Numeral 101 designates an input vector registerwhich holds input signal series in a block, numeral 102 a code tableaddress counter which forms address of a code table, numeral 103 anoutput vector code table memory which stores an output vector, numeral104 an output vector code table register which holds data read from theoutput vector code memory, numeral 105 a parallel subtractor whichcalculates the difference between the value of the input vector register101 and the value of the output vector code table register 104, numeral106 a parallel absolute value calculator which calculates the absolutevalue of output of the parallel subtractor, numeral 107 an absolutevalue distortion detector which detects the absolute value distortioninput/output vector, numeral 108 a minimum distortion detector whichdetects the output vector to minimize the absolute value of theinput/output vector, and numeral 109 an index latch which holds theindex of output vector to minimize distortion based on the output signalof the minimum distortion detector 108.

Operation of the prior art will be described. The input vector series ofK in number are brought together into a block of input vector x={x₁, x₂,. . . , x_(k) } and taken in the input vector register 101. Then, countup is effected to the code table address counter 102 in sequence up toi=1, 2, . . . , N, and the output vector y_(i) ={y_(i1), y_(i2), . . . ,y_(ik) } is read in sequence from the output vector code table memory103 and then latched to the output vector code table register 104. Theparallel subtractor 105, the parallel absolute value calculator 106 andthe absolute value distortion detector 107 estimate the absolute valuedistortion d_(i) of input/output vector for each output vector y_(i) inthe following operation. ##EQU8##

The minimum distortion detector 108 detects the output vector tominimize the absolute value distortion d_(i). The minimum distortion dis

    d=min d(x, y.sub.1)=min[Σ|x.sub.j -y.sub.ij |]

The minimum distortion detector 108 calculates the distortion d (x,y_(i)) between the output vector y_(i) read in sequence from the outputvector code table memory 103 and the input vector x, and compares thecalculated value with the minimum value in the past. If a smaller valueis detected, the minimum distortion detector 108 holds this value as thenew minimum distortion and transmits the strobe signal to the indexlatch 109 at evey time of holding and takes the index signal i being thecode table address of the output vector into the index latch 109. Theabove-mentioned procedure is continued until the output vector y_(i) isread entirely (i=1-N) from the output vector code table memory 103;thereby the full search is finished. Then, the index i of the outputvector to give the minimum distortion remains in the index latch, andthis becomes the encoding output.

The term "full search" is usually employed in the field of vectorquantization to mean such operation that distortion calculation anddistortion comparison are performed between all of the output vectors(y₁) to (y_(N)) thereby to obtain an output vector (y₁) showing theminimum distortion, when searching the output vector providing theminimum distortion to the input vector from the output vectors (y₁) to(y_(N)) which have previously been provided in a code table.

The above-mentioned apparatus is the full search vector quantizationmember to constitute the vector quantization encoding member.

The outline of the fifth embodiment will now be described.

In the fifth embodiment, allowable distortion is set to a distortiondiscrimination circuit, and when distance (distortion) between inputvector and output vector becomes less than the allowable distortionduring search of the output vector to give the minimum distortion, theindex signal of the output vector is converted in variable lengthencoding and the encoding output is obtained thereby the encodingefficiency is improved.

The fifth embodiment will be described specifically.

FIG. 23 is a block diagram illustrating the constitution of the fifthembodiment. In FIG. 23, numeral 310 designates a full search vectorquantization member having similar constitution to that described inFIG. 22 (hereinafter referred to as "FSVQ member" including FIG. 22 as awhole), numeral 320 a distortion discrimination circuit whichdiscriminates that the absolute value distortion d_(i) becomes less thanthe prescribed allowable distortion dθ, and numeral 330 a variablelength encoding circuit which converts the index signal i of the outputvector in variable length encoding and obtains the encoding output whenthe absolute value distortion d_(i) and the allowable distortion dθbecomes d_(i) ≦dθ based on the output signal of the distortiondiscrimination circuit.

FIG. 24 is a block diagram illustrating detailed constitution of theFSVQ member 310 in the fifth embodiment. In FIG. 24, similar parts tothose in FIG. 22 are designated by the same reference numerals. In placeof the code table address counter 102 shown in FIG. 22, a code tableaddress counter 102 with reset function is used and can be reset byoutput of the distortion discrimination circuit 320. The apparatus inFIG. 24 is similar to that in FIG. 22 except for the above-mentioneddifference.

Operation of the fifth embodiment in above-mentioned constitution willbe described.

In the decoding member, the input signal series of K in number arebrought together into a block of input vector x={x₁, x₂, . . . , x_(k) }and inputted to the FSVQ member 310. In the FSVQ member 310, the inputvector x is taken into the input vector register 101, and count-up iseffected to the code table counter 102 with reset function in sequenceup to i=1 to N; thereby the output vector y_(i) ={y_(i1), y_(i2), . . ., y_(ik) } is read from the output vector code table memory 103 and thenlatched in sequence to the output vector register 104.

Next, the parallel subtractor 105, the parallel absolute valuecalculator 106 and the absolute value distortion detector 107 estimatethe absolute value distortion d_(i) between the input vector x and eachoutput vector y_(i) as expressed in following formula. ##EQU9## Theminimum distortion detector 108 compares the absolute value distortiond_(i) with the minimum value in the past. If a smaller value isdetected, the minimum distortion detector 108 holds this value as newminimum distortion and outputs it to the distortion discriminationcircuit 320. The minimum distortion detector 108 transmits the strobesignal to the index latch 109 at every time of holding and takes theindex signal i being code table address of the output vector y_(i) intothe index latch 109 and then outputs it to the variable length encodingcircuit 330. The above-mentioned procedure is performed every time thecount of the code table address counter 102 with reset function issubjected to count-up from i=1 to N. The distortion discriminationcircuit 320, which receives the output d_(i) of the minimum distortiondetector 108, compares it with the prescribed allowable distortion dθ.When relation dθ≧d_(i) applies, the distortion discrimination circuit320 transmits the index latch signal to the variable length encodingcircuit 330 and makes the circuit 330 to take the index latch signal i.The distortion discrimination circuit 320 also transmits the resetsignal to the code table address counter 102 with reset function andfinishes the count and resets it to i=1. The variable length encodingcircuit 330 taking the index signal i entirely deletes "0" continuingfrom most significant bit of the index signal i to least significant bitthereby reducing the code length. Such procedure is performed in everyindex signal i taken therein, and variable length encoding is performed;thereby the encoding output is obtained.

According to the embodiment as above described, the distortion dibetween the input vector x and the output vector yi is compared with theprescribed allowable distortion dθ. When condition di≦dθ applies, thesearch is stopped and the index signal i of the output vector at thistime is converted in variable length encoding and the encoding output isobtained. Accordingly, the encoding efficiency is significantlyimproved; thereby the high speed processing is achieved.

Sixth Embodiment

Before describing a sixth embodiment of the invention specifically, treesearch vector quantization as background art of the sixth embodimentwill be described.

As shown in FIG. 30, studying a binary tree where two branches areseparated from each node R, a root of the tree corresponds toK-dimensional signal space R^(K) and each node corresponds to a space bypartitioning the space R^(K) stepwise. Each space has a representativepoint (e.g., center of gravity) which becomes a K-dimensional outputvector. Based on distribution of output vector and input vector in eachstep, the total amount of distortion between input/output vector isspecified to become minimum.

When input vector is given, in each of steps from the first step up tothe last step, distortion to output vector corresponding to twopartition nodes is compared and a branch with less distortion isselected; thereby the output vector corresponding to the node at thelast end is selected. If the last step is the n-th step, nodes at thelast end are 2^(n) in number. Tree search vector quantization (TSVQ) hasbeen described. FIG. 30 shows an example when n=3.

FIG. 25 shows a constitution example of a tree search vector quantizerat n=3. In FIG. 25, numeral V₁ designates input signal vector in a blockper every K ones, numeral 420 a first step of TSVQ encoder to which theinput signal vector is inputted, numeral V₃ first step output vectorindex outputted from the first step of TSVQ encoder, numeral 440 asecond step of TSVQ encoder to which the first step output vector indexis inputted, numeral V_(s) second stage output vector index outputtedfrom the second step of TSVQ encoder, numeral 460 a third step of TSVQencoder to which the second step output vector index is inputted, andnumeral V₇ third step output vector index outputted from the third stepof TSVQ encoder. FIG. 26 shows a detailed constitution example of thesecond step 440 of TSVQ. In FIG. 26, numeral 441 designates an inputvector register to which the input signal vector V₁ is inputted, numeral442 a second step output vector code table to which the output vectorindex V₃ is inputted, numeral 443 a distortion operation circuit whichcalculates distortion between the input signal outputted from the inputvector register 441 and the output vector index outputted from thesecond step output vector code table 442, numeral 445 a distortioncomparison circuit which estimates the minimum value of distortioncalculated by the distortion operation circuit 443, numeral V₉designates distortion comparison result signal outputted from thedistortion comparison circuit 445, and numeral 446 an index registerwhich outputs the second step output vector index V₅ based on thedistortion comparison result signal V₉ and the first step output vectorindex signal V₃.

Operation of the tree search vector quantizer will be described. Thetree search vector quantization is in repetition of procedure thatdistortion comparison between two output vectors in a pair and an inputsignal vector is performed at each step, and a pair of output vectors tobe compared at next step is determined. The distortion operation of thetree at three steps shown in FIG. 30 corresponds to the first step 420,the second step 440 and the third step 460 of TSVQ encoder shown in FIG.25. In each step, a distortion operation is performed between a pair ofoutput vectors assigned on the basis of distortion comparison results tothe previous step and an input vector and that of less distortion isdetermined, and the information is added to the comparison results ofthe previous step and then transmitted to the next step. Since the firststep has only one pair of output vectors, comparison results to theprevious step are not required and therefore do not exist. Assuming thatthe output index V₃ outputted on the basis of distortion comparisonresults in the first step be i₁, in the second step, distortionoperation is performed between a pair of output vectors determined by i₁and an input vector, and the comparison results are added to i₁ so as toform i₂ 5. In the third step, i₃ 7 is outputted by i₂ and input. In FIG.30, assuming that "0" is assigned if a branch at the left is selectedand "1" is assigned if a branch at the right is selected, indexes i₁,i₂, i₃ become the binary sequence of one column, two columns and threecolumns respectively, and vector i₃ of the binary sequence becomes theoutput vector index at the last step. Thus operation of the tree searchvector quantizer has been described.

The output vector code table in each step must store a pair of outputvectors assigned on the basis of results in the previous stage as shownin FIG. 29, that is, output vector index of y₀, y₁ at the first step,y₀₀, y₀₁, y₁₀, y₁₁ at the second step, and y₀₀₀, y₀₀₁, y₀₁₀, y₀₁₁, y₁₀₀,y₁₀₁, y₁₁₀, y₁₁₁ at the third step.

The outline of the sixth embodiment will now be described.

In the sixth embodiment, one of output vector indexes stored in a vectorcode table at initial step of an encoder is selected on the basis of aninitial pseudo output vector index and an input signal vector inputtedto the initial step of the encoder, and first step output vector indexis outputted from the initial step of the encoder.

Code "0" is added to upper position of output vector with shorter codelength so as to equalize the code length, and distortion between thepseudo output vector index with equalized code length and the inputsignal vector is calculated by an operation circuit.

Consequently, a vector code table of an encoder in each step can be madecommon.

The sixth embodiment will be described specifically in the case that asearch is performed at three steps and the initial pseudo index is "001"(BIN) referring to FIGS. 27 through 29.

FIG. 27 is a block diagram of a tree search vector quantization encoderof the embodiment where the search is performed at three steps. In FIG.27, similar parts to those in FIG. 25 are designated by the samereference numerals. In FIG. 27, numeral V₄ designates the initial pseudooutput vector index, numeral 420 a first step of TSVQ encoder in thesixth embodiment to which the initial pseudo output vector index V₄ andthe input signal vector are inputted, numeral V₆ first step pseudooutput vector index outputted from the first step 420 of TSVQ encoder,numeral 440 a second step of TSVQ encoder to which the input signalvector V₁ and the first step pseudo output vector index V₆ are inputted,numeral V₈ second step pseudo output vector index outputted from thesecond step 440 of TSVQ encoder, and numeral 460 a third step of TSVQencoder to which the input signal index V₁ and the second step outputvector index V₈ are inputted.

FIG. 28 is a block diagram of the second step of TSVQ encoder of theembodiment shown in detail. In FIG. 28, an output vector code table 442of the second step 440 of TSVQ encoder has a second step output vectorcode table #0 and a second step output vector code table #1.

The input signal vector V₁ is inputted through an input vector register441 to a distortion operation circuit 443. The distortion operationcircuit 443 calculates distortion between the vector index stored in thesecond step output vector code table #0 and the second step outputvector code table #1 and the input signal vector V₁, and inputs thecalculation results to a second step distortion comparison circuit 445.Based on the calculation results of the distortion operation circuit443, the second step distortion comparison circuit 445 outputs adistortion comparison result signal V₉ in "0" or "1", and the distortioncomparison result signal V₉ and the first step pseudo output vectorindex V₆ inputted to the output vector code table 442 are inputted to apseudo index shift register 446. The pseudo index shift register 446outputs a second step pseudo output vector index V₈.

The first step 420, the second step 440 and the third step 460 of TSVQencoder constitute a vector quantization apparatus 500 as a whole.

Operation of the sixth embodiment will be described when the initialpseudo index is made "001" (BIN). FIG. 29 shows address map when searchof the output vector code tables #0, #1 common to each search step isperformed in three steps. Distortion between the input signal vector V₁inputted to the first step of TSVQ and vector indexes y₀, y₁ outputtedfrom the output vector code tables #0, ·1 by the initial pseudo outputvector index V₄ being "001" (BIN) is calculated in the distortioncircuit 443. Based on the calculation results of the distortionoperation circuit 443, the distortion comparison circuit 445 selects oneoutput vector to give the minimum distortion and then outputs thedistortion comparison result signal V₉ based on the comparison results.The pseudo index shift register 446 adds the distortion comparisonresult signal V₉ to the least significant bit (LSB) of the first steppseudo output vector index V₆ and further truncates the most significantbit (MSB) and feeds the second pseudo output vector index to next step.Such procedure is further effected in the second step and third step,thereby in the third step pseudo index shift register, any of the leastsignificant bit (LSB) being "1" of the initial pseudo output vectorindex is truncated and the required third step output vector index V₇can be obtained. More specifically, in the first step, according to theinitial pseudo output vector index "001" (BIN), if the vector index y₀is outputted from the output vector code table #0 to the output vectorand the vector index y₁ is outputted from the output vector code table#1 thereto and the vector index y₀ of the output vector code table #0 isselected, the distortion comparison result signal V₉ becomes "0" and thepseudo index shift register 446 adds the least significant bit (LSB)being "0" of the initial pseudo output vector index V₄ being "001" andfurther truncates the most significant bit (MSB) being "0". This isexpressed as follows:

    001(BIN)→0010(BIN)→010(BIN)

In the second step of TSVQ encoder, according to the first step pseudooutput vector index V₆ being "010" (BIN), if the vector index y₀₀ isoutputted from the output vector code table #0 and the vector index y₀₁is outputted from the output vector code table #1 and the vector indexy₀₁ of the output vector code table #1 is selected, the second steppseudo output vector index V₈ becomes

    010(BIN)→0101(BIN)→101(BIN)

In the third step of TSVQ encoder, according to the second step pseudooutput vector index V₈ being "101" (BIN), if the vector indexes y₀₁₀,y₀₁₁ are outputted from the output vector code tables #0, #1respectively and the vector index y₀₁₁ of the output vector code table#1 is selected, it follows that

    101(BIN)→1011(BIN)→011(BIN)

Thus the initial pseudo output vector index disappears and the index"011" (BIN) of the vector index y₀₁₁ is obtained as the third stepoutput vector index (encoding output) V₇.

This search process coincides with the root in FIG. 27.

According to the embodiment as above described, code "0" is added by thenecessary number to the upper position of the output vector index withshorter code length so as to equalize the code length, and the initialpseudo output vector index being not overlapped with the pseudo outputvector index by equalizing the code length is inputted to the encoder atthe first step. In the vector code table of the encoder at each step,since the pseudo output vector and the initial pseudo output vectorindex are constituted by equalizing the code length, the memory contentto constitute the output vector code table in each step can be madecommon and therefore can be reduced.

Seventh Embodiment

Before describing a seventh embodiment of the invention specifically,background art as the basis of the seventh invention will be describedreferring to FIG. 31.

In FIG. 31, similar parts to those in FIGS. 1 through 30 are designatedby the same reference numerals. In FIG. 31, numeral Sg₁ designated avideo signal, numeral 6 a subtractor, numeral 3 a frame memory, numeral511 a transmission buffer, numeral 7 a mean value separation normalizingvector quantization encoder, numeral Sg₂ quantization output, numeral517 a variable length encoder, numeral Sg₃ encoding output, numeral 522a raster/block scan conversion member, numeral 523 a video signal block,numeral 524 a prediction error signal block, numeral 526 a reproductionprediction error signal block, numeral 527 a reproduction video signalblock, and numeral Sg₄ a feedback control signal.

Operation of an interframe vector quantization encoder shown in FIG. 31will be described. The video signal Sg₁ is digitized and a signal seriesis given in sequence of the raster scan direction. The raster/block scanconversion member 522 partitions the video signal Sg₁ into K blocks (K:integer), and performs the scan conversion in sequence of the block as aunit. Assume that the video signal block 523 in block formation in f-thframe is expressed as S=(S₁, S₂, . . . , S_(k)). Further, if theprediction error signal block 525 as the difference between the videosignal block 523 calculated by the subtracter 6 and the predictionsignal block 524 is made e_(f), the reproduction prediction error signalblock 526 formed by the mean value separation normalizing vectorquantization encoder 7 and the mean value separation normalizing vectorquantization encoder 9 is made e_(f), the reproduction video signalblock 527 is made S_(f), and the prediction signal block 524 obtained asthe reproduction video signal block 527 supplied with delay of one frameperiod by the frame memory 3 is made P_(f), it follows that

    e.sub.f =S.sub.f -P.sub.f

    e.sub.f =e.sub.f +Q

    S.sub.f =P.sub.f +e.sub.f =S.sub.f +Q

    P.sub.f =S.sub.f ·Z.sup.-t

Wherein, Q represents vector quantization error, and Z^(-t) representsdelay of one frame period by the frame memory 3. This is basically aDPCM system (difference pulse modulation system) between frames. Thequantization output S_(g2) of the mean value separation normalizingvector quantization encoder 7 is converted in variable length encodingby the variable length encoder 517, and then transmitted to thetransmission buffer 511 and outputted as the encoding output Sg₃ to thetransmission path. The transmission buffer 511 supervises thetransmission information amount, and controls the threshold value in themean value separation normalizing vector quantization encoder 7 by thefeedback control signal S_(g4) so as to control the encoding dataamount.

The mean value separation normalizing vector quantization encoding isdescribed in detail in "T. Murakami, K. Asai, E. Yamazaki: HighEfficiency Endoding of Picture Image by Vector Quantization, report inNo. 6 symposium regarding the information theory and its application(1983) pp. 77-82" (reference 1) and "T. Murakami, K. Asai: VectorQuantizer of Video Signal, published by the Institute of TelevisionEngineers in Japan (1984) pp. 452-457" (reference 2). Consequently, thedetailed description shall be omitted here.

Outline of the seventh embodiment will now be described.

In an interframe vector quantization encoder of the seventh embodiment,significance/insignificance discrimination is performed to predictionerror signal series the difference between frames of the video signal,and only significant picture elements are brought together into a blockand mean value separation normalizing vector quantization encoding isperformed. Accordingly, noise in block formation is reduced in the videosignals and the video transmission is achieved at high quality.

The seventh embodiment will be described specifically referring to FIG.32.

FIG. 32 is a block diagram of an interframe vector quantization encoderin the seventh embodiment. In FIG. 32, similar parts to those in FIGS. 1through 31 are designated by the same reference numerals. In FIG. 32,numeral 3 designates a frame memory, numeral S_(g5) prediction signalseries, numeral S_(g6) prediction error signal series, numeral 560 araster circuit, numeral S_(g7) reproduction prediction error signalseries, numeral S_(g8) reproduction video signal series, numeral 590 asignificance/insignificance discrimination circuit, numeral 510 a blockcircuit, numeral 511 a transmission buffer, numeral S_(g9) a feedbackcontrol signal, numeral S_(g10) significance/insignificance information,numeral S_(g11) a block signal, numeral 7 a mean value separationnormalizing vector quantization encoder, numeral S_(g2) quantizationoutput, numeral 517 a variable length encoder, numeral S_(g3) encodingoutput, numeral 9 a mean value separation normalizing vectorquantization decoder, numeral S_(g12) a reproduction block signal, andnumeral 10 an adder.

Operation of the interframe vector quantization encoder of the seventhembodiment shown in FIG. 32 will be described. If the raster scan videosignal S_(g1) in the f-th frame is made input signal series S_(rf), theprediction error signal series S_(g6) as difference between the inputsignal series S_(rf) calculated by the subtractor 6 and P_(rf) of theprediction signal series S_(g5) from the frame memory 3 is made e_(rf),the reproduction prediction error signal series S_(g7) reproduced by theraster circuit 560 is made e_(rf), the reproduction video signal seriesS_(g8) is made S_(rf), and prediction signal series S_(g5) obtained asthe reproduction video signal series supplied with delay of one frameperiod by the frame memory 3 is made P_(rf), it follows that

    e.sub.rf =S.sub.rf -P.sub.rf

    e.sub.rf =e.sub.rf +Q

    S.sub.rf =P.sub.rf +e.sub.rf =S.sub.rf +Q

    P.sub.rf =S.sub.rf ·Z.sup.-t

Wherein, Q represents vector quantization error, and Z^(-t) representsdelay of one frame period by the frame memory 3. This is basically DPCMsystem between frames. In the DPCM system between frames, the predictionerror signal series S_(g6) calculated by the subtractor 6 is inputted tothe significance/insignificance discrimination circuit 590 and the blockconstituting circuit 510. In the significance/insignificancediscrimination circuit 590, the threshold value is set by the feedbackcontrol signal S_(g9) from the transmission buffer 511 and thesignificance/insignificance information S_(g10) (e.g., significance is"1" and insignificance is "0") is outputted. The block constitutingcircuit 510 takes the prediction error signal series S_(g6) and thesignificance/insignificance information S_(g10), and only the pictureelements deemed to be significant are brought together per K elements(K: plural number) into the block signal S_(g11) as x=(x₁, x₂, . . . ,x_(R)) and then outputted. If the number of the significant pictureelements within one frame does not become a multiple of K, dummy data(e.g., "0") is inserted to constitute one block. The mean valueseparation normalizing vector quantization encoder 7 taking the blocksignal S_(g11) quantizes the block signal S_(g11) by mean value,variance and index and makes it quantization output S_(g2). The variablelength encoder 517 converts the quantization output S_(g2) and thesignificance/insignificance information S_(g10) in variable lengthencoding. In one method, for example, the significance/insignificanceinformation S_(g10) is converted into run length encoding, and thequantization output S_(g2) is assigned with codes having short codelength for data of high appearing frequency and with codes having longcode length for data of low appearing frequency. The transmission buffer511 inputting these codes transmits the codes as encoding output S_(g3)to the transmission path and totalizes the information amount at anyperiod (e.g., per frame or per field) and outputs the feedback controlsignal S_(g9) by the totalization into the significance/insignificancediscrimination circuit 590 so as to control the information amount. Inthe mean value separation normalizing vector quantization decoder 9,from the quantization output S_(g2) quantized by mean value, varianceand index, the reproduction block signal S_(g12) is encoded andreproduced as x=(x₁, x₂, . . . , x_(R)). By the raster circuit 560taking the significance/insignificance information S_(g10), componentsx₁, x₂, . . . , x_(R) of x of the reproduction block signal S_(g12) areassigned only to the significant picture element, and code "0" isassigned to the insignificant picture elements, thereby e_(rf) of thereproduction prediction error signal series S_(g7) is reproduced. Theadder 10 adds e_(rf) of the reproduction prediction error signal seriesS_(g7) to P_(rf) of the prediction signal series S_(g5) from the framememory 3, and the added output is stored as S_(rf) of the reproductionvideo signal series S_(g8) to the frame memory 3.

According to the embodiment as above described, in the interframe vectorquantization encoder, significance/insignificance discrimination isperformed to the prediction error signal series being the differencebetween frames of the video signal, and only the significant pictureelements are brought together into a block and the mean value separationnormalizing vector quantization encoding is performed. Accordingly,noise in block formation is reduced in the video signal and the videotransmission at high quality is achieved.

Eighth Embodiment

Before describing an eighth embodiment of the invention specifically,background art as the basis of the eighth embodiment will be describedreferring to FIGS. 33 and 34.

FIG. 33 is a block diagram of a motion video transmission apparatus asbackground art of the eighth embodiment. In FIG. 33, similar parts tothose in FIGS. 1 through 32 are designated by the same referencenumerals. In FIG. 33, numeral Sg₁ designates digital video input data,numeral 630 an input double buffer, numeral 640 a transmission doublebuffer, numeral 517 a variable length encoder, numeral 760 a receivingdouble buffer, numeral 770 a variable length decoder, numeral 780 anoutput double buffer, numeral 900 a monitor, numeral Sg₂₀ video outputdata, numeral 810 a transmission path, numeral Sg₃₀ a camerasynchronization signal, numeral Sg₄₀ a transmission double bufferchanging signal, and numeral Sg₅₀ a monitor synchronization signal. Theinput double buffer 630, the variable length encoder 517 and thetransmission double buffer 640 are installed within a video transmitter600.

FIG. 34 is a timing chart illustrating operation of the apparatus inFIG. 33. In FIG. 34, W represents writing of the buffer, R representsreading from the buffer, and . . . , (n-1), (n), (n+1), . . . representthe number of transmitted frames.

Operation of the apparatus in the prior art will be described.

At the transmitting side, the digital video data Sg₁ is inputted fromthe camera 8 continuously at intervals of camera synchronization andwritten to the input double buffer 630 ("double buffer" beinghereinafter referred to as "DB") on one side thereof (A side) by anamount corresponding to one frame. Then, the transmission DB640 writesthe preceding frame data and reads the further preceding data. As soonas these procedures are finished, the changing of read/write of theinput DB630 is performed and the video data are read for encoding. Whilethe reading for encoding is performed, the input data Sg₁ from thecamera 8 are not written in the input double buffer 630 but aresubjected to time lapse. Subsequently, the next video data from thecamera 8 corresponding to one frame are written to the other side (Bside) of the input DB630, and a similar operation is repeated. Next, thevideo data read from the input DB630 are encoded by the variable lengthencoder 517 and written to one side (C side) of the transmission DB640.Then at other side (D side) of the transmission DB640, the video data ofthe preceding frame is read and transmitted to the transmission path810. As soon as reading and writing in the transmission DB640 arefinished, the changing of read/write is performed and the written dataare read out and transmitted. A similar operation is repeated. In thecase that encoding is performed at variable length and the transmissiontime varies, the time from start of reading by the input DB630 up tofinishing of writing to the transmission DB640 is made less than theminimum value of the transmission time, thereby the transmission isperformed without lowering the transmission efficiency.

On the other hand, at the receiving side, received data is written toone side (E side) of the receiving DB760. At other side (F side), dataof the preceding frame is read thereto for decoding and the reading ispreviously finished. When the writing is finished, the changing ofread/write of the receiving DB760 is performed, and the reading ofwritten data and writing of the next data are started. A similaroperation is repeated. The data read from the receiving DB760 is decodedby the variable length decoder 770, and written to one side (G side) ofthe output DB780. At other side (H side), corresponding tosynchronization of the monitor 900, reading of the preceding frame datais repeated and made the video output Sg₂₀. The output DB780 changesread/write at the break of next monitor output after ending of writing,and reads the written data and outputs it to the monitor 900. Writing tothe output DB780 is started when next decoding data comes. A similaroperation is repeated.

In the motion video transmission apparatus as above described, the timefrom inputting of the picture image from the camera 8 at transmissionside (time W(n) of the input DB630) up to starting of the transmission(the beginning of R(n) of the transmission DB640) nearly becomes the sumof the preceding transmission time and the further precedingtransmission time (R(n-1) and R(n-2) of the transmission DB640)subtracted by one synchronization time, and the interval of time lapse(interval from W(n) to W(n+1) of the input DB630) nearly becomes thetransmission time of the further preceding frame (R(n-2) of thetransmission DB640). Moreover, the time of the frame reproduced to themonitor 900 at the receiving side (repetition time of R(n) of the outputDB780) nearly becomes the receiving time of next frame (time of W(n+1)of the receiving DB760).

The outline of the eighth embodiment will now be described.

In the eighth embodiment, per every frame subjected to time lapse in aninput double buffer, different time intervals correspond to reading timeof the preceding frame read depending on the state of a transmissiondouble path from a transmission buffer. Depending on the writing time ofa receiving buffer being the same as the reading time, the number ofrepeated reading times of one frame in the output buffer is controlled.Consequently, the time-lapse picture image is reproduced as a smoothpicture image without lowering the transmission efficiency.

The eighth embodiment will be described referring to FIGS. 35 through37.

In FIGS. 35 through 37, similar parts to those in FIGS. 1 through 34 aredesignated by the same reference numerals and the detailed descriptionwill be omitted. Numeral 650 designates an input double buffer controldevice installed at the side of a transmitter 600. The input doublebuffer control device 650 corresponds to input buffer control means, andoutputs the input double buffer control signal Sg₆₀ based on camerasynchronous signal Sg₃₀ and transmission double buffer changing signalSg₄₀, and thereby controls the input double buffer 630 in read/write andchanging. On the other hand, numeral 790 designates an output doublebuffer control device installed at the side of a receiver 700. Theoutput double buffer control device 790 corresponds to output buffercontrol means, and outputs the output double buffer control signal Sg₈₀on monitor synchronous signal Sg₅₀ and receiving double buffer changingsignal SG₇₀, and thereby controls the output double buffer 780 inread/write and changing.

The operation of the eighth embodiment in the abovementionedconstitution will be described, referring to a timing chart shown inFIG. 36.

At transmitting side, the digital video data Sg₁ is inputted from thecamera 8 continuously at intervals of camera synchronization and writtento the input Db630 on one side (A side) per frame repeatedly. Thepreviously written data is erased at the next writing and updated. Theinput DB630 is changed at the break of next camera input after thewriting and reading at the transmission DB640 are finished, and theinput DB630 reads data written finally. Then at other side (B side) ofthe input DB630, writing is started and a similar operation is repeated.Data read from the input DB630 is transmitted in an operation similar tothe prior art. In this case, the time from the starting of reading bythe input DB630 up to the finishing of writing to the transmission DB640added by one frame time of the camera is made less than the minimumvalue of the transmission time; thereby the transmission can beperformed without lowering the transmission efficiency.

At the receiving side, operation of the receiving DB760 is similar tothe background art of FIGS. 33 and 34. Data is decoded by the variablelength decoder 770, and then written to one side (G side) of the outputDB780. At other side (H side) of the output DB780, data of the precedingframe is read in synchronization with the monitor 900 repeatedly, andoutputs the read data as the video output data Sg₂₀. The number ofreading times corresponding to the receiving time of the previous frame,i.e., the writing time of the receiving DB760 (equal to the transmissiontime, i.e., the reading time of the transmission DB640) is previouslystored, and outputting is performed by the stored number.

Count of the number of reading times is achieved, for example, bycircuit the constitution shown in FIG. 37. In this constitution, thenumber of times of the monitor synchronization during W(n-i) of thereceiving DB760 shown in FIG. 36 is counted. In FIG. 37, numeral 810designates a counter, numeral 820 a latch, numeral 830 a memory, numeralSG₁₀₀ a receiving DB changing pulse, numeral Sg₂₀₀ a monitorsynchronization pulse, numeral Sg₃₀₀ the count value of the counter 810,and numeral Sg₄₀₀ the output of the latch 820. The value in Sg₄₀₀represents the number of reading times corresponding to the receivingtime, and is stored to the memory 830.

Subsequently, the changing of read/write of the output DB780 isperformed, and a similar operation is repeated. If writing to the outputDB780 of the following frame is not finished even at exceeding thenumber of reading times of the output DB780, the number of reading timesis increased. On the contrary, if writing to the receiving DB760 offurther following frame is finished before attaining to the number ofreading times, reading from the receiving DB760 is delayed and thenumber of reading times of the output DB780 is decreased, thereby thevideo output Sg₂₀ is continuously outputted in adaptation.

In the motion video transmission apparatus of the eighth embodiment asabove described, the time from inputting of the picture image form thecamera 8 at transmission side up to the starting of the transmission andthe interval of time lapse nearly become the transmission time of thepreceding frame (R(n-1) of the transmission DB640. Moreover, the time ofthe frame reproduced to the monitor 900 at the receiving side iscontrolled to become nearly the receiving time of the preceding frame(W(n-1) of the receiving DB760; thereby these become nearly equal(transmission time≈receiving time). According, the time-lapse pictureimage is reproduced as a smooth picture image without lowering thetransmission efficiency.

Although the double buffer is installed as output buffer in theembodiment, if timing of writing and reading is difficult to be taken intime relation, the buffer may be controlled at three times or more. Thisapplies also to the other buffers.

According to the eighth embodiment as above described, the input doublebuffer is controlled in read/write and changing based on the camerasynchronization signal and the changing signal of the transmissiondouble buffer, and the video data from the camera is updated per frameand written and the changing of write/read is performed from the nextframe after the changing of the transmission double buffer by the inputdouble buffer control means. The output double buffer is controlled inread/write and the changing based on the monitor synchronization signaland the changing signal of the receiving double buffer, and the numberof repeated reading times in the output double buffer corresponds to thewriting time of the preceding frame to the receiving double buffer bythe output double buffer control means. Accordingly, the time-lapsepicture image is reproduced as a smooth picture image without loweringthe transmission efficiency.

What is claimed is:
 1. A vector quantization apparatus wherein a binarytree k-dimensional vector space has n steps and 2 branches arepartitioned from each node of each step and nodes of 2^(n) in number areprovided at the n-th step, and when input signal vectors formed in ablock per every k elements and an output vector index corresponding toinputted branches are inputted to nodes of a space R^(k), a vector codetable which selects one branch among branches partitioned from each nodeand outputs the output vector index corresponding to the selected branchand stores in a vector code index the output vector corresponding toeach branch partitioned from the node, and a distortion operationcircuit which calculates distortion between each vector index stored insaid vector code index and the input signal vector and estimates theoutput vector index to minimize the distortion, are provided in anencoder of each step, and an output vector index is outputted from anencoder of the following step based on the output vector index outputtedfrom the encoder of each step and the input vector and the output vectorindex outputted from the n-th step is estimated, characterized in thatan initial pseudo output vector index which is not overlapped with apseudo output vector index having equality of code length achieved byadding code "0" at the upper position of the output vector index ofshorter code length is inputted to the encoder of the first step, and apair of output vectors designated by the pseudo output vector index andthe initial pseudo output vector index has the vector code table of theencoders of other steps.
 2. A vector quantization apparatus as set forthin claim 1, wherein the initial pseudo output vector index comprises "1"(BIN) at least significant bit only, and "0" (BIN) in the requirednumber at higher order bit or bits.
 3. A vector quantization apparatusas set forth in claim 1, wherein a required number of encoders areconnected in series, each encoder comrising:an input vector register forreceiving an input vector; a vector code table for adding a requirednumber of codes "0" to upper bits of said output vector index and makingit pseudo output vector index so that bit length of the pseudo outputvector index is coincident with that of said output vector index to beestimated and outputting two vectors corresponding to two points at thebranch front of the binary tree using the inputted pseudo output vectorindex as address input; a distortion operation circuit for calculatingdistortion between the two output vectors and the input vector; adistortion comparison circuit for comparing two distortions calculatedby said distortion operation circuit and outputting a distortioncomparison result signal ("1" or "0"); and a pseudo index shift registerfor shifting the inputted pseudo output vector index by one bit to theupper bit direction and deleting the most significant bit and adding thedistortion comparison result signal as the least significant bit andoutputting it as pseudo output vector index; and further the initialpseudo output vector index to be inputted to the first step is set sothat all pseudo output vector indexes to be inputted to each step arenot overlapped with each other.
 4. A vector quantization apparatus asset forth in claim 1, wherein all output vectors using the pseudo outputvector index as address are stored in vector code tables of the encodersof all steps.